The principle of changing the title of a tkinter main root window is the same as what we discussed in the previous recipe: How to create independent message boxes. We just pass in a string as the first argument to the constructor of the widget.
The following code creates the main window and adds a title to it. We have already done this in the previous recipes, for example, in Creating tabbed widgets, in Chapter 2, Layout Management. Here we just focus on this aspect of our GUI:
import tkinter as tk
win = tk.Tk() # Create instance
win.title("Python GUI") # Add a title